JP2000141552A - White weatherable laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly weatherable laminated film almost free from the deterioration of whiteness by forming an ultraviolet-absorbing layer on at least one of the faces of a white base material film. SOLUTION: A white base material film is obtained by adding a thermoplastic resin and a noncompatible resin with the thermoplastic resin or a white inorganic pigment and biaxially stretching the mixture after the melting and extrusion thereof. The thermoplastic resin is preferably a polyester resin. In addition, an ultraviolet-absorbing layer is formed on at least one of the faces of the white base material film, and may be of a single layer form or of a multilayer form. This ultraviolet-absorbing layer is obtained by adding any appropriate ultraviolet-absorbing agent, e.g. an ultraviolet-shielding agent of benzotriazole or the like to a resin component such as a thermoplastic, a heat- curable or an active radiation-curable resin or copolymerizing the resin component with the ultraviolet-absorbing agent. Besides, the anchoring process is not particularly specified, provided, however, that it enhance the adhesive properties of a base material with the ultraviolet-absorbing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white weather-resistant laminated film, and more particularly to a white weather-resistant laminated film having excellent whiteness and weather resistance.

[0002]

2. Description of the Related Art Heretofore, as a white film, a film in which white inorganic particles are filled in a polyester resin and a fluorescent whitening agent is used in combination as needed has been often used. For example, Japanese Patent Publication No.
No. 4901 and Japanese Patent Publication No. Sho 4 with addition of calcium carbonate
The invention described in, for example, JP-A-3-12013 is disclosed. Further, a resin obtained by adding a polyolefin resin to a polyester resin is also disclosed in JP-A-63-172740.

[0003]

However, these conventional white films suffer from a fatal drawback for white films, in that the whiteness, which is a characteristic feature of the conventional white films, is reduced due to deterioration of the polyester resin or polyolefin resin serving as a skeleton due to ultraviolet rays. Because it had, especially in outdoor applications,
Limited use.

[0004] The present invention is to improve the above-mentioned drawbacks, and to provide a white weather resistant laminated film which has little decrease in whiteness and surface deterioration even in outdoor use and is extremely excellent in weather resistance.

[0005]

That is, the present invention is based on a white weather-resistant laminated film characterized in that an ultraviolet absorbing layer is provided on at least one surface of a white base film.

Hereinafter, the present invention will be described in detail.

[0007] The white base film referred to in the present invention is a film obtained by incorporating a thermoplastic resin and an incompatible resin or a white inorganic pigment, melt-extruding and then biaxially stretching. As the thermoplastic resin, polyester resin, polypropylene, polyolefin resin such as polyethylene, polyamide resin represented by nylon, etc., polyvinyl chloride resin, polycarbonate resin,
Acrylic resin, fluorine resin, or the like can be used. Among them, polyester resin is preferable from the viewpoint of mechanical strength, dimensional stability and the like.

[0008] Polyester resin is a generic term for polymers having an ester bond as a main bonding chain. Particularly preferred polyester resins include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, and polybutylene. -2,6 naphthalate and the like can be used, and among these, polyethylene terephthalate can be preferably used in view of quality and economy. This polyethylene terephthalate is used as a main component, and a single core layer may be used. However, a laminated film composed of two layers of a core layer and an outer layer, preferably three layers having outer layers on both sides of the core layer is desirable.

Here, the term "polyethylene terephthalate as the main constituent" means that 80% by weight or more of the resin component constituting the white base film is made of polyethylene terephthalate, more preferably 85% by weight or more. And more preferably 90% by weight or more of polyethylene terephthalate. Other components that can be mixed with the polyethylene terephthalate are polyester resins other than the above main components, and specifically, various copolymers of polyester are preferable.

As a method for imparting whiteness to the white base film of the present invention, there are a method of adding a resin having poor compatibility with the resin as a main component and a method of containing a white inorganic pigment. Generally, the latter method of containing a white inorganic pigment is widely used.

As the white inorganic pigment, those conventionally used can be used, and for example, titanium dioxide, barium sulfate, zinc oxide, calcium carbonate and the like can be preferably used. The amount of the inorganic pigment to be added can be adjusted depending on the type of the pigment in order to obtain the desired whiteness. For example, when obtaining a whiteness of 80% or more of the laminated film after the weather resistance deterioration test described in the present application, 7 to 15% by weight of titanium dioxide on the core film side and 2 to 10% on the outer layer.
Contains titanium dioxide by weight. Alternatively, it can be achieved by including 10 to 20% by weight of barium sulfate or calcium carbonate in the core film and 2 to 20% by weight of titanium dioxide in the outer layer. Here, it is preferable that the white inorganic pigment added to the outer layer has a small particle size, and that the amount added is smaller than that of the core film, because the surface gloss of the white base film can be excellent. The particle diameter of the white inorganic pigment is preferably 1 μm or less, more preferably 0.5 μm or less, and most preferably 0.3 μm or less in terms of whiteness.

As for the method of adding a resin having poor compatibility with the resin of the main component, for example, in the case of a polyethylene terephthalate film, a resin incompatible with polyethylene terephthalate as a resin component constituting the base film is used. A resin that exhibits a phase-separated structure in a sheet state after kneading. As a typical example, a polyolefin resin can be used. Specifically, low density to high density polyethylene, isotactic, atactic, syndiotactic polypropylene, polymethylpentene, polystyrene and the like can be used. These immiscible resins are dispersed and compounded in the polyethylene terephthalate in the base film, and the compounding ratio is usually high in consideration of productivity, mechanical strength while utilizing the characteristics of whiteness and low density. 3% by weight or more and 30% by weight or less, more preferably 5% by weight or more and 25% by weight or less, and most preferably 7% by weight or more and 25% by weight or more. Such a polyester film in which the incompatible resin is dispersed and blended forms a fine cavity with the incompatible resin as a core by being biaxially stretched.

The thickness of the white substrate film of the present invention may be freely set according to the intended use, and is usually 25 to 250 μm.
A range of m is common and desirable. The thickness of the outer layer is desirably 2 μm or more and 50 μm or less, preferably 3 μm or more and 20 μm or less from the viewpoint of whiteness.

In the present invention, an ultraviolet absorbing layer is formed on at least one surface of the white base film. The ultraviolet absorbing layer may be a single layer or a plurality of layers. In the case of a plurality of layers, any one of the layers is preferably a layer containing an ultraviolet absorber, and preferably two or more layers are layers containing an ultraviolet absorber from the viewpoint of maintaining weather resistance.

The ultraviolet absorbing layer is made of thermoplastic, thermosetting,
Suitable UV absorbers in the resin component such as active ray-curable resin, for example, benzophenone-based, benzotriazole-based, triazine-based, cyanoacrylate-based, salicylate-based, benzoate-based, oxalic anilide-based or inorganic UV-screening agents And the like can be obtained by laminating a resin contained or copolymerized in a resin.

Particularly, in the present invention, a suitable ultraviolet absorber is a benzotriazole-based ultraviolet absorber.

In the present invention, the surface of the white base film is subjected to various discharge treatments, oxidation treatments, roughening treatments, anchor coating treatments, etc. in order to improve the adhesion between the white base film and the ultraviolet absorbing layer. preferable.

The anchoring treatment is not particularly limited as long as it improves the adhesiveness between the substrate and the ultraviolet absorbing layer.
For example, use of at least one selected from urea resin, melamine resin, urethane resin, polyester resin, acrylic resin, silicon resin, epoxy resin, and the like, and using a thermosetting resin layer containing these resins as a main component and adding a crosslinking agent. Can be. Of course, it is more preferable to include a weather resistance imparting agent in this anchor coat layer.

As the UV absorbing layer component formed on at least one surface of the white base film, an acrylic resin containing benzotriazole UV absorbing monomer copolymerized methyl methacrylate as a main component is preferable. By adding a melamine resin curing agent to the benzotriazole-based UV-absorbing monomer copolymerized acrylic resin, the UV-absorbing layer can be used preferably in a single layer, but preferably has a multilayer structure.

The benzotriazole-based UV-absorbing monomer copolymerized acrylic resin is a resin obtained by copolymerizing a benzotriazole-based reactive monomer with an acrylic monomer and / or oligomer, and the obtained polymer may be an organic solvent. Any form such as a soluble form or a water dispersible form may be used.

As the benzotriazole-based monomer,
Any monomer having benzotriazole in the substrate skeleton and having an unsaturated double bond may be used, and is not particularly limited, but a preferred monomer is 2- (2'-hydroxy-5'-acryloyloxyethylphenyl) -2H −
Benzotriazole, 2- (2'-hydroxy-5'-
(Methacryloxyethylphenyl) -2H-benzotriazole, 2- (2'-hydroxy-3'-tert-
Butyl-5'-acryloyloxyethylphenyl)-
5-chloro-2H-benzotriazole is preferred. The acrylic monomers and / or oligomers copolymerized with these monomers include alkyl acrylates and alkyl methacrylates (alkyl groups include methyl, ethyl, n-propyl, isopropyl,
a monomer having an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, a lauryl group, a stearyl group, a cyclohexyl group, and the like;
For example, carboxyl group, methylol group, acid anhydride group, sulfonic acid group, amide group, or methylolated amide group, amino group (including substituted amino group), alkylolated amino group, hydroxyl group, epoxy group, etc. Can be exemplified. Examples of the monomer having the above functional group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylsulfonic acid, styrenesulfonic acid, acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide, Methylolated methacrylamide, diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether,
2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, and those obtained by converting the amino group to methylol, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxyvinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate,
Examples include polyethylene glycol monomethacrylate, glycidyl acrylate, and glycidyl methacrylate, but are not necessarily limited thereto. In addition to the above, the following monomers such as acrylonitrile, methacrylonitrile, styrene, butyl vinyl ether, mono or dialkyl esters of maleic acid and itaconic acid, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl Pyrrolidone, alkoxysilane having a vinyl group, and polyester having an unsaturated bond may be used as the copolymerization component.

In obtaining the white weather-resistant laminated film of the present invention, one or more of the above-mentioned acrylic monomers and / or oligomers may be copolymerized in any ratio, but preferably, methyl methacrylate or Styrene is at least 20% by weight of the acrylic monomer,
More preferably, 30% by weight or more is copolymerized from the viewpoint of the hardness of the laminated film. The copolymerization ratio of the benzotriazole-based monomer and the acrylic monomer is such that the ratio of the benzotriazole-based monomer is from 10% by weight to 70% by weight, preferably from 20% by weight to 65% by weight, more preferably from 25% by weight to 60% by weight. It is preferable that the content is not more than weight% in terms of weather resistance, adhesion to a base film, and durability. The molecular weight of the copolymer is not particularly limited, but is preferably 5000 or more, more preferably 100 or more.
It is preferably at least 00 in view of the durability of the laminated film. The copolymer can be produced by, for example, a method such as radical polymerization, and is not particularly limited. The copolymer is laminated on a substrate film as an organic solvent or a water dispersion, the thickness is usually 0.5 to
It is preferably in the range of 10 μm, preferably in the range of 0.7 to 7 μm, more preferably in the range of 1 to 5 μm from the viewpoint of weather resistance, flexibility and the like.

In the present invention, the surface of the weather-resistant resin layer composed of a single layer or a plurality of layers preferably has a pencil hardness of H or more, more preferably 2H or more, and most preferably 3H or more. . When the pencil hardness is less than H, the surface is apt to be scratched when exposed to the outdoors, and the appearance and gloss are reduced, which is not preferable.

In order to obtain such a surface hardness, it is possible to use an acrylic, epoxy, silicone, organic silicate, urethane, inorganic compound or the like as a constituent component. In consideration of flexibility, an acrylic resin is preferable, and an actinic ray-curable acrylic resin is particularly preferable.

The actinic ray-curable acrylic resin contains an actinic ray-curable polymerizable component containing an acrylic oligomer and a reactive diluent, and optionally, a photoinitiator, a photosensitizer,
A modifier may be contained.

As the acrylic oligomer, those in which a reactive acrylic group is bonded to an acrylic resin skeleton, polyester acryl, urethane acryl, epoxy acryl, polyether acryl, and the like, and melamine, isocyanuric acid, and the like can be used. A rigid skeleton having an acrylic group bonded thereto may be used, but the present invention is not limited thereto.

The reactive diluent functions as a medium for the coating agent, that is, a solvent for the coating step.
It is possible to use one which itself has a group which reacts with a monofunctional or polyfunctional acrylic oligomer and which becomes a copolymer component of a coating film.

In particular, in the case of crosslinking by ultraviolet rays, since the light energy is small, it is preferable to add a photopolymerization initiator and / or a sensitizer to promote the conversion and initiation of the light energy.

Specific examples of the above-mentioned acrylic oligomer, reactive diluent, photopolymerization initiator, sensitizer, crosslinking device, etc.
Shinzo Yamashita and Tosuke Kaneko, "Handbook of Crosslinking Agents", Taiseisha 1980, pp. 267-275, 56
Pages 2 to 593 can be referenced, but are not limited thereto. Commercially available polyfunctional acrylic actinic radiation curable coatings include Mitsubishi Rayon Co., Ltd., Fujikura Kasei Co., Ltd., Dainichi Seika Kogyo Co., Ltd., Dainippon Ink and Chemicals Co., Ltd., Toa Gosei Co., Ltd. Products such as Nippon Kayaku Co., Ltd. can be used, but not limited thereto.

In the present invention, one example of a material for forming a surface hardness layer which can obtain a particularly preferable surface hardness is, for example, at least one monomer having three or more (meth) acryloyloxy groups in one molecule. An actinic radiation-curable product having as a main component an actinic radiation-curable monomer composition comprising at least one monomer having 1 to 2 ethylenically unsaturated double bonds in the molecule, Can be used. This is preferable because it is excellent in hardness and curability, and is also excellent in scratch resistance and flexibility.

As a monomer having three or more (meth) acryloyloxy groups in one molecule, a polyhydric alcohol having three or more alcoholic hydroxyl groups in one molecule has three or more (meth) hydroxyl groups. A compound which is an esterified product of acrylic acid can be used. For example, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate And dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and trimethylolpropane tri (meth) acrylate. These monomers can be used alone or in combination of two or more.

The proportion of the monomer having three or more (meth) acryloyloxy groups in one molecule is preferably 20 to 90% by weight based on the total amount of the polymerizable monomer. More preferably, 30 to 80% by weight. Most preferably 30-7
0% by weight.

The proportion of the monomer used is 20% by weight.
When the amount is less than 90%, the cured film is inferior in scratch resistance, and when the amount exceeds 90% by weight, the film largely shrinks due to polymerization, and the film remains undesirably deformed, resulting in poor flexibility.

In the present invention, the monomer having one or two ethylenically unsaturated double bonds in one molecule is not particularly limited as long as it is a normal monomer having radical polymerizability. can do.

Examples of the compound having two ethylenically unsaturated double bonds in one molecule include the following (a) to (f).
(A) C2 to C12 alkylene glycol (meth) acrylic acid diesters: ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth)
Acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, etc. (b) (meth) acrylate diesters of polyoxyalkylene glycol: diethylene glycol di (meth) acrylate, triethylene glycol Di (meta)
(C) (meth) acrylic acid diester of polyhydric alcohol such as acrylate, tetraethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate : Pentaerythritol di (meth) acrylate, etc. (d) Bisphenol A or (meth) acrylic acid diesters of ethylene oxide and propylene oxide adducts of hydrogenated bisphenol A: 2,2'-bis (4-acrylic acid) Roxyethoxyphenyl) propane,
2,2'-bis (4-acryloxypropoxyphenyl) propane and the like (e) A terminal isocyanate group-containing compound obtained by previously reacting a diisocyanate compound with two or more alcoholic hydroxyl group-containing compounds, further comprising an alcoholic hydroxyl group-containing compound (F) Compounds having two or more epoxy groups in the molecule, such as urethane (meth) acrylates having two or more (meth) acryloyloxy groups in the molecule obtained by reacting (meth) acrylate, Epoxy (meth) acrylates having two or more (meth) acryloyloxy groups in the molecule obtained by reacting an acid or methacrylic acid can be preferably used in the present invention.

Examples of the compound having one ethylenically unsaturated double bond in one molecule include methyl (meth) acrylate, ethyl (meth) acrylate, n- and i-propyl (meth) acrylate, n-, sec. −, And t
-Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, polyethylene glycol Mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, N-hydroxyethyl (meth)
Acrylamide, N-vinyl-3-methylpyrrolidone,
N-vinyl-5-methylpyrrolidone or the like can be used. These monomers may be used alone or in combination of two or more. The usage ratio of the monomer having 1 to 2 ethylenically unsaturated double bonds in one molecule is based on the total amount of the monomer.
Preferably from 10 to 80% by weight, more preferably from 20 to 7%.
0% by weight. If the proportion of the monomer used exceeds 80% by weight, it is difficult to obtain a cured film having sufficient scratch resistance, which is not preferable. On the other hand, if the proportion is less than 10% by weight, the flexibility of the film is undesirably reduced.

It is preferable that the surface hardening layer contains an ultraviolet absorber, and the above-mentioned ultraviolet absorber can be added. In the case of forming the surface hardened layer, those having a functional group which reacts with actinic rays, for example, an ultraviolet absorber having an unsaturated bond is preferable.

Examples of the ultraviolet absorber having such an unsaturated group include benzophenone-based and benzotriazole-based ultraviolet absorbers. Among them, 2-
(2'-hydroxy-5'-acryloyloxyethylphenyl) -2H-benzotriazole, 2- (2 '
-Hydroxy-5'-methacryloxyethylphenyl)
-2H-benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-acryloyloxyethylphenyl) -5-chloro-2H-benzotriazole, 2-hydroxy-4- (2-acryloyloxy ) Ethoxybenzophenone, 2,2'-dihydroxy-4- (2-acryloyloxy) ethoxybenzophenone and the like are preferred. UV absorbers containing such unsaturated groups, when used in combination with the above-mentioned actinic ray-curable acrylic, react with each other by actinic rays such as ultraviolet rays and electron beams to impart excellent weather resistance and scratch resistance. You can do it.

The amount of the ultraviolet absorber to be added is preferably 1 to 50 parts by weight with respect to the actinic ray-curable monomer composition.
More preferably, it is 3 to 30 parts by weight. If the addition amount of the ultraviolet absorber is small, the weather resistance is poor, and if the addition amount is too large, the curing reaction by the actinic ray may not be sufficiently performed, and the film may not have sufficient hardness.

In the present invention, as a method of curing the active ray-curable monomer composition used, for example, a method of irradiating ultraviolet rays can be used. In this case, the active ray-curable monomer composition is used. It is preferable to add a photopolymerization initiator to the mixture.

Examples of the photopolymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone,
4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
Methyl benzoinmate, p-isopropyl-α-
Carbonyl compounds such as hydroxyisobutylphenone, α-hydroxyisobutylphenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, thioxanthone, 2-chlorothioxanthone, Sulfur compounds such as 2-methylthioxanthone and peroxide compounds such as benzoyl peroxide and di-t-butyl peroxide can be used.

These photopolymerization initiators may be used alone or in combination of two or more. The use amount of the photopolymerization initiator is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the actinic ray-curable monomer composition. When electron beam or gamma ray is used as the curing means, it is not always necessary to add a polymerization initiator.

In the present invention, the actinic ray-curable monomer composition to be used includes hydroquinone, hydroquinone monomethyl ether, 2,5-t-butyl for the purpose of preventing thermal polymerization during production and dark reaction during storage. It is preferable to add a thermal polymerization inhibitor such as hydroquinone. The amount added is preferably 0.005 to 0.05% by weight based on the total weight of the actinic ray-curable monomer composition.

The actinic ray-curable monomer composition to be used contains an organic solvent for the purpose of improving workability at the time of coating and controlling the coating film thickness within a range that does not impair the effects of the present invention. Can be compounded. As the organic solvent, those having a boiling point of 50 to 160 ° C. are preferably used from the viewpoint of workability during coating and drying before and after curing. For example, alcohol solvents such as isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, and the like. Ketone solvents,
Examples include aromatic solvents such as toluene and saturated hydrocarbon solvents such as cyclohexanone. These solvents can be used alone or in combination of two or more.

The actinic ray-curable monomer composition used in the present invention may contain additives such as an antioxidant, a light stabilizer, a leveling agent and an antistatic agent as long as the effects of the present invention are not impaired. May be blended.

For the purpose of preventing the reflection of the laminated film, fine particles such as colloidal silica, alumina sol and acrylic resin may be added.

As a method of applying the actinic ray-curable monomer composition, for example, brush coating, dip coating, knife coating, roll coating, spray coating, spin coating (eg, spinner) and the like can be used.

The actinic radiation used in practicing the present invention is an electromagnetic wave such as an ultraviolet ray, an electron beam, or a radiation (α ray, β ray, γ ray, etc.) capable of polymerizing an acrylic vinyl group. Ultraviolet light is simple and preferable, and as an ultraviolet light source,
For example, an ultraviolet fluorescent lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a carbon arc lamp, and the like can be used. In addition, the electron beam method requires an expensive device and requires an operation under an inert gas, but from the viewpoint that it is not necessary to include a photopolymerization initiator or a photosensitizer in the surface hardness layer. It can be preferably used.

At the time of the curing reaction of the actinic ray-curable monomer composition, nitrogen gas is introduced into the atmosphere to reduce the oxygen concentration, thereby enabling curing with low energy. In particular, in the present invention, an ultraviolet absorber is added to impart weather resistance, and in order to rapidly perform the curing in a curing reaction by ultraviolet rays, nitrogen gas is introduced into the atmosphere and the oxygen concentration is reduced to 10% or less. Is desirable.

The thickness of the weather-resistant surface hardened layer obtained by the above method is not particularly limited and is appropriately determined depending on the application. Usually, the thickness is preferably 0.5 μm or more and 10 μm, more preferably 2 μm. ６6 μm. If the thickness of the surface hardness layer is less than 1 μm, the surface hardness is insufficient and the surface is easily damaged, and if it exceeds 10 μm, the cured film becomes brittle, which is not preferable.

As described above, by providing an ultraviolet absorbing layer having a pencil hardness of H or more on the white base film, the whiteness of the white weather-resistant laminated film is higher than that of the white base film alone, and particularly, the wavelength is 295 to 450 nm. , Illuminance 100mW / c
The effect is remarkable after the weathering deterioration accelerating test irradiated with m ² ultraviolet rays.

[0052]

[Measurement and evaluation of characteristics] (A) Accelerated weathering deterioration test Ultraviolet light deterioration accelerating tester (I-Super UV Tester S
Using UV-W131 (manufactured by Iwasaki Electric Co., Ltd.), an irradiation cycle test was performed under the following conditions, and the change in color tone, whiteness, tensile strength and elongation of the film were evaluated.

Light 8 hours (UV illuminance: 100 mW / c
m ² temperature / humidity: 60 ° C. × 50% RH) → dew 4 hours (temperature / humidity: 35 ° C. × 100% RH dew condensation), 12 hours as one irradiation cycle, and the characteristics before and after 10 cycles of irradiation were evaluated.

(B) Change in the color of the film The change in the color of the film after the irradiation with the Eye Super UV tester was judged with the naked eye.

：: No change.

Δ: slightly yellowish

×: Changed to yellow-brown.

(C) Whiteness According to JIS L1015, a Hitachi automatic recording spectrophotometer U3
Using a Model 410, the reflectances R (450)% and R (55) of the film at wavelengths of 450 nm and 550 nm, respectively.
0)% was calculated from the following equation.

Whiteness (%) = 4R (450) -3R (550) (d) Tensile strength / elongation According to JIS C2318, using Tensilon, a tensile speed of 200 mm / min, a test length of 50 mm, and a width of 5 mm. The tensile strength and elongation of the strip film were measured.

(E) Pencil hardness According to JIS K5400, the surface of the laminated film was scratched with pencils of various hardnesses, and the pencil hardness was indicated immediately before scratching.

[0061]

The present invention will be described below in more detail with reference to examples.

Example 1 Using a composite film forming apparatus comprising a main extruder and a sub-extruder, a polyethylene terephthalate resin containing 10% by weight of barium sulfate having an average particle diameter of 0.5 μm was added to the main extruder, and a sub-extruder A polyethylene terephthalate resin containing 5% by weight of titanium dioxide having an average particle diameter of 0.2 μm was previously vacuum-dried at 180 ° C. for 3 hours, and then dried at 270 to 270 ° C.
The mixture was supplied to two extruders heated to 300 ° C., melt-extruded from a T-die, and formed into a sheet having a main / sub thickness ratio of 90/10 on a mirror cast drum by an electrostatic application method.
This sheet is led to a group of rolls heated to 85 to 95 ° C,
The film was longitudinally stretched 3.5 times in the longitudinal direction and cooled with a roll group at 25 ° C.

Subsequently, the longitudinally stretched film was guided to a tenter while holding both ends of the film with clips, and was horizontally stretched 3.6 times in a direction perpendicular to the longitudinal direction in an atmosphere heated to 90 to 130 ° C. Thereafter, heat fixation at 230 ° C. is performed in a tenter, and the film is gradually cooled, cooled to room temperature, and wound up to obtain a composite white film having a core thickness of 90 μm, an outer layer thickness of 5 μm each for cast and non-cast surfaces, and a total thickness of 100 μm. Was.

On one side of the obtained film, a layer A having the following composition was applied so that the thickness after application was 2 μm.
It was dried at 120 ° C. for 1 minute. Further, a layer having a weather-resistant surface hardness layer (B) having the following composition and having a thickness of 4 μm after curing is formed on the layer A.
m, and the solvent was dried with a hot air dryer at 80 ° C., and then cured by irradiating 300 mJ / cm ² of ultraviolet light with a conveyor-type metahalide lamp (manufactured by Eye Graphic Co., Ltd.).

After the test for accelerating weathering deterioration, there was no change in the tint, and there was no significant decrease in whiteness, tensile strength and elongation before and after the accelerating test for weathering deterioration.

(A) Layer Coating Composition 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole (30 wt%) copolymerized methyl methacrylate 95 parts Modified saturated polyester resin (Nippon Chemical Co., Ltd. Nikkacoat FS-12) 4 parts Methylated melamine (Mitsui Cytec Co., Ltd. Cymel 370) 1 part Toluene / methyl ethyl ketone = 1: 1 400 parts Coating composition of layer (B) 2- (2'-hydroxy-5) '-Methacryloxyethylphenyl) -2H-benzotriazole 20 parts Dipentaerythritol hexaacrylate 68 parts Acrylic oligomer (Kyoeisha Chemical Aronix M-7100) 8 parts 2-hydroxypropyl acrylate 4 parts Irgacure 183 (manufactured by Ciba Geigy) 4 parts toluene / Methyl ethyl ketone = 1: 312 parts Example 2 A single-layer white film having a thickness of 100 µm produced in the same manner as in Example 1 using the raw material of the main extruder was obtained using only the main extruder without using the sub-extruder. . On one side of the obtained film, the layer A having the same composition as in Example 1 was applied to have a thickness of 2 μm.
And dried at 120 ° C. for 1 minute. further,
The weather-resistant surface-hardened layer (B) of Example 1 was applied on this A layer so that the thickness after curing was 4 μm, and the solvent was dried with a hot-air dryer at 80 ° C., and then a conveyor-type metahalide. 300m UV light with lamp (I-Graphics)
The composition was irradiated with J / cm ² and cured.

After the test for accelerating weathering deterioration, there was no change in tint, and no significant decrease in whiteness, tensile strength and elongation was observed before and after the accelerating test for weathering deterioration.

Example 3 The ultraviolet absorbent (2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-) in the layer B of Example 1
Example 3 in which benzotriazole) was not added was used. After the test for accelerating weathering deterioration, there was no change in the color tone, and no significant decrease in whiteness, tensile strength and elongation was observed before and after the test for accelerating weathering deterioration.

Example 4 In place of the ultraviolet absorber (2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole) in the layer B of Example 1, 2- (2'-hydroxy −5′-methacryloxyethylphenyl) -2H-benzotriazole (50 wt%) copolymerized methyl methacrylate was added.

After the test for accelerating weathering deterioration, there was no change in the color tone, and no significant decrease in whiteness, tensile strength and elongation was observed before and after the accelerating test for weathering deterioration.

Example 5 Instead of the layer B in Example 1, Kayanova POP-062 manufactured by Nippon Kayaku Co., Ltd. was applied so that the thickness after application was 4 μm.

After the test for accelerating weathering deterioration, there was no change in the tint, and there was no significant decrease in whiteness, tensile strength and elongation before and after the accelerating test for weathering deterioration.

Example 6 In place of the raw material of the main extruder of Example 2, a raw material mixed so as to be 89% by weight of polyethylene terephthalate resin, 1% by weight of polyethylene glycol having a molecular weight of 4000, and 10% by weight of polymethylpentene was used. In the same manner as in Example 2, a white weather-resistant laminated film was produced. This is referred to as Example 5.

Even after the test for accelerating the deterioration of the weather resistance, the change in the color tone is very slight, and there is no practical problem. In addition, there is no significant decrease in whiteness, tensile strength and elongation before and after the weather resistance deterioration acceleration test.

Example 7 One side of the white film of Example 1 was coated with 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-
Benzotriazole (50 wt%), methyl methacrylate (32 wt%), butyl acrylate (17 wt%)
%), 97 wt% of acrylic acid (1 wt%) copolymer resin and 3 wt% of methylated melamine resin in a toluene / methyl ethyl ketone solution (resin concentration: 20 wt%) so as to have a thickness of 4 μm after application, and 120 ° C. for 1 minute Dried.

After the test for accelerating weathering deterioration, there was no change in the color tone, and no significant decrease in whiteness, tensile strength and elongation was observed before and after the accelerating test for weathering deterioration.

COMPARATIVE EXAMPLE 1 Comparative Example 1 was made using only the multilayer white film obtained in Example 1.

After the test for accelerating weathering deterioration, the film turned slightly yellow, and before and after the accelerating test for deterioration in weathering, the whiteness and the tensile strength decreased. In addition, the tensile elongation is greatly reduced.

Comparative Example 2 A single-layer white film obtained in Example 2 alone is referred to as Comparative Example 2.

After the test for accelerating weathering deterioration, the film turned yellow-brown, and before and after the test for accelerating weathering deterioration, the whiteness and tensile strength also decreased. Further, the tensile elongation is greatly reduced, and the deterioration is remarkable.

Comparative Example 3 A single-layer white film obtained in Example 5 alone is referred to as Comparative Example 5.

After the test for accelerating weathering deterioration, the film turned yellow-brown, and before and after the test for accelerating weathering deterioration, the whiteness and tensile strength also decreased. Further, the tensile elongation is greatly reduced, and the deterioration is remarkable.

Table 1 shows the results of evaluating various properties of the white weather-resistant laminated films of the above Examples and Comparative Examples.

It can be seen that the white weather-resistant laminated film of the present invention has excellent weather resistance.

[0085]

[Table 1]

Continued on front page F-term (reference) 4F100 AA07H AA21H AH03B AH03C AK01A AK04 AK07 AK25B AK25C AK42 AK44 AL01B AL01C AR00A AR00B AR00C BA02 BA03 BA08 BA07 BA10A BA10C BA25B BA25C BA44A CA07BCA07 E08 JD09C JK12B JK12C JL09 JL10A YY00B YY00C YY00H 4F207 AA04 AA21 AA24 AB06 AB14 AB16 AC01 AD05 AD08 AD32 AG01 AG03 AH46 KA01 KB26 KE06 KF02 4F210 AA04 AA04 AA21 AA24 AB06 Q14 AD03 Q05 Q05 AD03 Q05 Q08

Claims (6)

[Claims] 1. A white weather-resistant laminated film, wherein an ultraviolet absorbing layer is provided on at least one surface of a white base film. 2. A white base film containing a thermoplastic resin and an incompatible resin or a white inorganic pigment.
The white weather-resistant laminated film according to claim 1, which is a film obtained by stretching in a biaxial direction after melt extrusion. 3. The white weather-resistant laminate according to claim 1, wherein the ultraviolet absorbing layer comprises one or more layers, and at least one layer contains an ultraviolet absorbing agent. the film. 4. The white weather-resistant laminated film according to claim 1, wherein the ultraviolet absorbing layer is a layer made of a benzotriazole-based ultraviolet absorbing monomer copolymerized acrylic resin. 5. The white weather-resistant laminated film according to claim 1, wherein the ultraviolet absorbing layer has a surface hardness of pencil hardness H or more. 6. The ultraviolet absorbing layer has a thickness of 0.5 μm or more,
The thickness is not more than 10 μm.
The white weather-resistant laminated film according to 3, 4, or 5.